Airlock assemblies have been used in space operations for human cargo space vehicles such as the U.S. Space Shuttle, as well as for space station entry and egress. Nearly all airlock assemblies are rigid wall structures that have a volume appropriate to the egress/ingress requirements of the items or humans to be accommodated. This type of rigid structure airlock is very time inefficient for ingress and egress, consumes space, expends excess energy, and loses a significant amount of air with each cycle.
Other airlock designs include shaped airlocks which are essentially a Rigid Chamber airlocks, except the rigid chamber is shaped to match the shape of the payload. By shaping the rigid chamber, the volume to be evacuated and pressurized during egress and ingress is reduced, thereby reducing the drawbacks of the Rigid Chamber airlock. However, with this design, the airlock is effective with only those items of a size and shape to match the rigid chamber.
Another airlock design is a Plastic Displacement airlock system which comprises a chamber and some plastic or fluid material that floods the chamber to displace the air. This greatly reduces the air lost on each cycle. However, the amount of plastic material required to flood the chamber can result in excess weight, and it is not clear how the plastic material can be controlled to prevent it from spilling into the interior or exterior of the vehicle.
Lastly, Suit Dock airlock systems have been designed which comprise a space suit and a docking mechanism between the space suit and the space vehicle. With this design, the suit never enters the vehicle, and the astronaut must climb out of the suit and through the dock to enter the vehicle. This design allows for better dust control, as when used on a planetary surface. It also reduces cycle time, energy consumption, and air loss. However, it is strictly limited to moving personnel into and out of the space vehicle.
More recently, a Conformal Airlock Assembly and Method have been developed, which is the subject of U.S. Pat. Nos. 7,997,537 and 8,251,316, filed Oct. 7, 2007 and Jul. 19, 2011, respectively, and herein both incorporated by reference in their entirety. While these conformal airlock inventions addressed many of the problems associated with the above-mentioned airlock designs, the volumetric space required to implement these airlocks is not suitable for extremely small interior spacecraft, especially where useable space is at a premium.
Accordingly, there is a need for a simple, compact airlock assembly and method for use in space operations where storage and living space is at a premium.